CN108511144B

CN108511144B - Soft magnetic alloy and magnetic component

Info

Publication number: CN108511144B
Application number: CN201810161975.0A
Authority: CN
Inventors: 吉留和宏; 松元裕之; 堀野贤治; 长谷川晓斗; 米泽祐; 后藤将太; 天野一
Original assignee: TDK Corp
Current assignee: TDK Corp
Priority date: 2017-02-27
Filing date: 2018-02-26
Publication date: 2020-05-12
Anticipated expiration: 2038-02-26
Also published as: TWI669403B; JP6245394B1; TW201831705A; KR20180099498A; US10943718B2; KR101998514B1; CN108511144A; EP3366790A1; US20180247745A1; JP2018142602A

Abstract

The invention provides a soft magnetic alloy which contains Fe as a main component and C. In the continuous measurement range of the soft magnetic alloy, the amount of Fe in 80000 lattices of 1nm × 1nm × 1nm is greater than the average composition of the soft magnetic alloy, and the domains are composed of a network phase of Fe composition connected together. The average value of the C content in the lattice having an Fe content lower than the average value is 5.0 times or more the average C content of the whole soft magnetic alloy, counted from the lattice having a low C content, and the cumulative frequency is 90% or more.

Description

Soft magnetic alloy and magnetic component

Technical Field

The present invention relates to a soft magnetic alloy and a magnetic component.

Background

In recent years, in electronic, information, communication devices and the like, there has been a demand for lower power consumption and higher efficiency. Further, the demand is becoming stronger as the low-carbon society is developed. Therefore, power supply circuits for electronic, information, communication devices, and the like are also seeking to reduce energy loss and improve power supply efficiency. Further, improvement of magnetic permeability and reduction of core loss (core loss) are demanded for a core of a ceramic element used for a power supply circuit. If the core loss is reduced, the loss of electric energy is reduced, and high efficiency and energy saving can be achieved.

Patent document 1 describes a technique for obtaining a soft magnetic alloy powder having a large magnetic permeability and a small core loss and suitable for a magnetic core by changing the particle shape of the powder. However, magnetic cores having higher magnetic permeability and smaller core loss are being sought.

Patent document 1: japanese laid-open patent publication No. 2000-30924

Disclosure of Invention

As a method of reducing the core loss of the magnetic core, a method of reducing the coercive force of a magnetic material constituting the magnetic core is considered.

The invention aims to provide a soft magnetic alloy with low coercive force and high manufacturing stability.

Means for solving the problems

In order to achieve the above object, a soft magnetic alloy according to the present invention in a first aspect contains Fe as a main component and C, and is characterized in that:

in the composition of the soft magnetic alloy Fe_aCu_bM1_cSi_dB_eC_fWherein a + b + c + d + e + f is 100, b is more than or equal to 0.1 and less than or equal to 3.0, c is more than or equal to 1.0 and less than or equal to 10.0, d is more than or equal to 0.0 and less than or equal to 17.5, e is more than or equal to 6.0 and less than or equal to 13.0, f is more than 0.0 and less than or equal to 4.0, M1 is more than or equal to one selected from Nb, Ti, Zr, Hf, V, Ta, Mo, P and Cr,

in regard to the Fe amount of 80000 lattices of 1nm × 1nm × 1nm in the continuous measurement range of the soft magnetic alloy, a region having a larger amount of Fe than the average composition of the soft magnetic alloy is composed of a network phase of Fe composition connected together,

the average value of the C content in the lattice having an integrated frequency of 90% or more is 5.0 times or more the average C content of the whole soft magnetic alloy, counted from the lattice having a low Fe content and a low C content.

The soft magnetic alloy of the present invention in the first aspect has the above-described Fe compositional network phase, and the distribution of the amount of C in the lattice having a small amount of Fe is set as described above, whereby the coercive force is reduced and the manufacturing stability is improved.

In the soft magnetic alloy according to the present invention in the first aspect, it is preferable that the average M1 content in the lattice having the cumulative frequency of 90% or more, counted from the start of the lattice having a lower Fe content than the average, be 1.2 times or more the average M1 content of the entire soft magnetic alloy.

In order to achieve the above object, a soft magnetic alloy according to the present invention in a second aspect contains Fe as a main component and C,

in the composition of the soft magnetic alloy Fe_αM2_βB_γC_ΩWherein α + β + gamma + omega is 100, 1.0 is not less than β is not more than 15.0, 2.0 is not less than gamma is not less than 20.0, 0.0 is more than omega is not less than 4.0, M2 is more than one selected from Nb, Cu, Zr, Hf, Ti, V, Ta, Mo, P, Si and Cr,

in the continuous measurement range of the soft magnetic alloy, the amount of Fe in 80000 lattices of 1nm × 1nm × 1nm is greater than the average composition of the soft magnetic alloy, and the domains are composed of a network phase of Fe composition connected together,

the average value of the amount of C in the lattice having an integrated frequency of 90% or more is 5.0 times or more the average amount of C in the whole soft magnetic alloy, counted from the lattice having a low amount of C in the lattice having a lower Fe amount than the average amount.

The soft magnetic alloy of the present invention in the second aspect has the above-described Fe compositional network phase, and the distribution of the amount of C in the lattice having a small amount of Fe is set as described above, whereby the coercive force is reduced and the manufacturing stability is improved.

In the soft magnetic alloy of the present invention in the second aspect, the average M2 content in the lattice whose Fe content is lower than the average is preferably 1.2 times or more the average M1 content of the whole soft magnetic alloy, as counted from the lattice whose C content is low.

The following description is common to the first and second aspects.

The average C content of the soft magnetic alloy as a whole is preferably 3 atomic% or less.

The average B amount in the lattice having an Fe amount lower than the average is preferably 1.2 times or more the average B amount of the whole soft magnetic alloy, as counted from the lattice having a low C content, and the cumulative frequency is preferably 90% or more.

The magnetic member of the present invention is composed of the soft magnetic alloy.

Drawings

Fig. 1 is a photograph showing the Fe concentration distribution of a soft magnetic alloy according to an embodiment of the present invention observed with a three-dimensional atom probe.

Fig. 2 is a photograph showing a model of a network structure of a soft magnetic alloy according to an embodiment of the present invention.

Fig. 3 is a schematic diagram of a process of searching for a local maximum point.

Fig. 4 is a schematic diagram showing a state in which line segments connecting all the local maximum points are generated.

Fig. 5 is a schematic view showing a state after dividing into a region in which the Fe content exceeds the average value and a region below the average value.

Fig. 6 is a schematic view of a state in which a line segment passing through a region in which the Fe content is equal to or less than the average value is deleted.

Fig. 7 is a schematic view of a state in which the longest line segment among the line segments forming the triangle is deleted in the case where there is no portion in the triangle where the Fe content is equal to or less than the average value.

FIG. 8 is a schematic of a single roll process.

Fig. 9 is a graph showing the relationship between the carbon concentration and the integrated frequency.

Description of the symbols

10 … … cell

10a … … maximum point

10b … … adjacent lattices

Region with 20a … … Fe content above threshold

Region where 20b … … Fe content is not more than threshold value

31 … … nozzle

32 … … molten metal

33 … … roller

34 … … thin strip

35 … … Chamber

36 … … stripping gas injection device

Detailed Description

Embodiments of the present invention will be described below.

The soft magnetic alloy of the present embodiment is a soft magnetic alloy containing Fe as a main component. Specifically, "containing Fe as a main component" refers to a soft magnetic alloy in which the content of Fe is 65 atomic% or more of the total soft magnetic alloy.

The composition of the soft magnetic alloy of the present embodiment is not particularly limited, except for the point that Fe is the main component. Although Fe-Si-M1-B-Cu-C soft magnetic alloy and Fe-M2-B-C soft magnetic alloy are exemplified, other soft magnetic alloys may be used.

In the following description, the content of each element in the soft magnetic alloy is, in particular, 100 atomic% in the total soft magnetic alloy when no parameter is described.

In the case of using a soft magnetic alloy of Fe-Si-M1-B-Cu-C system, the composition of the soft magnetic alloy of Fe-Si-M1-B-Cu-C system is expressed as Fe_aCu_bM1_cSi_dB_eC_fIn the case of (2), the following formula is preferably satisfied. By satisfying the following formula, the network phase composed of Fe tends to be easily obtained. Further, a soft magnetic alloy having a low coercive force tends to be easily obtained. In addition, the raw material of the soft magnetic alloy composed of the following composition is relatively inexpensive.

a+b+c+d+e+f＝100

0.1≤b≤3.0

1.0≤c≤10.0

0.0≤d≤17.5

6.0≤e≤13.0

0.0＜f≤4.0

The Cu content (b) is preferably 0.1 to 3.0 atomic%, more preferably 0.5 to 1.5 atomic%. Further, as the Cu content is smaller, a thin strip made of a soft magnetic alloy tends to be easily produced by a single-roll method described later. By adding Cu in the above range, the coercive force can be reduced and the manufacturing stability can be improved.

M1 is a transition metal element or P. M1 may be at least one selected from Nb, Ti, Zr, Hf, V, Ta, Mo, P and Cr. The transition metal element is preferably one or more selected from the group consisting of Nb, Ti, Zr, Hf, V, Ta and Mo. Further, as M, Nb is preferably contained.

The content (c) of M1 is preferably 1.0 to 10.0 atomic%, more preferably 3.0 to 5.0 atomic%. By adding M1 within the above range, the coercive force can be reduced and the manufacturing stability can be improved.

The content (d) of Si is preferably 0.0 to 17.5 atomic%. When M ═ P, it is preferably 0.0 to 8.0 atomic%, and when M1 is a transition metal element, it is preferably 11.5 to 17.5 atomic%. By adding Si in the above range, the coercive force can be reduced and the manufacturing stability can be improved.

The content (e) of B is preferably 6.0 to 13.0 atomic%, more preferably 9.0 to 11.0 atomic%. By adding B within the above range, the coercive force can be reduced and the manufacturing stability can be improved.

The content (f) of C is preferably 0.0 to 4.0 atomic% (excluding 0.0 atomic%), more preferably 0.1 to 4.0 atomic%. By adding C within the above range, the coercive force can be reduced and the manufacturing stability can be improved.

Fe can be said to be the remainder of the soft magnetic alloy of Fe-Si-M1-B-Cu-C system according to this embodiment.

In the case of using a soft magnetic alloy of Fe-M2-B-C system, the composition of the soft magnetic alloy of Fe-M2-B-C system is expressed as Fe_αM2_βB_γC_ΩIn the case of (2), the following formula is preferably satisfied. By satisfying the following formula, the network phase composed of Fe tends to be easily obtained. Further, a soft magnetic alloy having a low coercive force tends to be easily obtained. In addition, the raw material of the soft magnetic alloy composed of the following composition is relatively inexpensive.

α+β+γ+Ω＝100

1.0≤β≤15.0

2.0≤γ≤20.0

0.0＜Ω≤4.0

M2 is a transition metal element or P. M2 may be at least one selected from the group consisting of Nb, Cu, Zr, Hf, Ti, V, Ta, Mo, P, Si and Cr. M2 is preferably a transition metal element, more preferably at least one element selected from Nb, Cu, Zr, Hf, Ti, V, Ta, Mo, P, and Cr, and even more preferably at least one element selected from Nb, Cu, Zr, and Hf. Further, M preferably contains one or more selected from Nb, Zr, and Hf.

The content (β) of M2 is preferably 1.0 to 15.0 atomic%, more preferably 1.0 to 14.1 atomic%, and still more preferably 5.0 to 8.1 atomic%.

The Cu content of M2 is preferably 0.0 to 2.0 atomic%, and more preferably 0.1 to 1.0 atomic%, based on 100 atomic% of the total soft magnetic alloy. Among them, when the content of M2 is less than 7.0 atomic%, Cu may be preferably not contained.

The content (. gamma.) of B is preferably 2.0 to 20.0 atomic%. Further, it is preferably 4.5 to 18.0 atomic% when Nb is contained as M2, and 2.0 to 8.0 atomic% when Zr and/or Hf is contained as M2. The smaller the content of B, the more amorphous the composition tends to be. When the content of B is within a predetermined range, the coercive force can be reduced and the manufacturing stability can be improved.

The content (Ω) of C is preferably 0.1 to 5.0 atomic%, more preferably 0.1 to 3.0 atomic%, and still more preferably 0.5 to 1.0 atomic%. The addition of C tends to improve amorphousness. When the content of C is within a predetermined range, the coercive force can be reduced, and the manufacturing stability can be improved.

Here, the Fe composition network phase included in the soft magnetic alloy of the present embodiment will be described. In the following description, in the case of using a soft magnetic alloy of Fe-Si-M1-B-Cu-C system, M is replaced with M1, and in the case of using a soft magnetic alloy of Fe-M2-B-C system, M is replaced with M2.

The Fe compositional network phase is a phase in which the content of Fe is higher than the average composition of the soft magnetic alloy. When the Fe concentration distribution of the soft magnetic alloy of the present embodiment is observed at a thickness of 5nm using a three-dimensional atom probe (hereinafter, sometimes referred to as 3DAP), a state in which a portion having a high Fe content is in a network-like distribution is observed as shown in fig. 1. Fig. 2 is a schematic diagram of the distribution after three-dimensionality.

In the conventional Fe-containing soft magnetic alloy, a plurality of portions having a high Fe content are each in a spherical shape or a substantially spherical shape, and are present in a seventy-eight manner through portions having a low Fe content. As shown in fig. 2, the soft magnetic alloy of the present embodiment has a characteristic that the portion having a high Fe content is continuously distributed in a network shape.

Next, a method of analyzing the Fe composition network phase and a criterion for determining the presence or absence of the Fe network phase in the present embodiment will be described.

First, a rectangular solid having a length of 50nm × 40nm × 40nm on each side is set as a measurement range, and the rectangular solid is divided into cells each having a rectangular solid shape with a length of 1 side of 1 nm. That is, there are 50 × 40 × 40 ═ 80000 cells in one measurement range. In the measurement range of the present embodiment, the shape of the measurement range is not particularly limited as long as 80000 cells that are finally present are continuously present.

Next, the Fe content in each lattice was evaluated. Then, the average value of the Fe content in all the lattices was calculated. The average value of the Fe content is substantially equal to a value calculated from the average composition of each soft magnetic alloy.

Next, a lattice having an Fe content exceeding a threshold value and having an Fe content higher than that of all adjacent lattices is set as a maximum point. Fig. 3 shows a model showing a step of searching for a local maximum point. The number shown inside each cell 10 indicates the Fe content contained in each cell. The lattice having an Fe content equal to or higher than the Fe content of all adjacent lattices 10b is set as a maximum point 10 a.

In fig. 3, 8 adjacent lattices 10b are described with respect to 1 local maximum point 10a, but actually, 9 adjacent lattices 10b are present in front of and at the depth of the local maximum point 10a in fig. 3. That is, there are 26 adjacent lattices 10b with respect to one maximum point 10 a.

It is to be noted that the grid 10 located at the end of the measurement range is considered to have a grid with an Fe content of 0 outside the measurement range.

Next, as shown in fig. 4, a line segment connecting all the local maximum points 10a included in the measurement range is generated. When connecting the line segments, the centers of the lattices are connected. In fig. 4 to 7, the local maximum point 10a is represented by a circle for convenience of description. The number recorded inside the circle is the Fe content.

Next, as shown in fig. 5, a region 20a in which the Fe content is higher than the threshold value (Fe composition network phase) and a region 20b in which the Fe content is equal to or lower than the threshold value are distinguished. Then, as shown in fig. 6, the line segment passing through the area 20b is deleted.

Next, as shown in fig. 7, when there is no area 20b inside the triangle, which is a portion where a line segment constitutes a triangle, the longest line segment among the three line segments constituting the triangle is deleted. Finally, in the case where the local maximum points are located in adjacent lattices, the line segment connecting the local maximum points is deleted.

The number of line segments extending from each local maximum point 10a is set as the coordination number of each local maximum point 10 a. For example, in the case of fig. 7, the coordination number of maximum point 10a1 having an Fe content of 50 is 4, and the coordination number of maximum point 10a2 having an Fe content of 41 is 2.

In the case where the lattice present on the outermost surface in the measurement range of 50nm × 40nm × 40nm represents a local maximum point, the local maximum point is excluded from the calculation of the proportion of local maximum points in a specific range of coordination number, which will be described later.

Further, the maximum point of the coordination number 0 and a region in which the Fe content existing around the maximum point of the coordination number 0 is higher than a threshold value are also included in the Fe composition network phase.

The measurement described above can be performed several times in different measurement ranges, and the accuracy of the calculated result can be sufficiently improved. It is preferable to perform 3 or more measurements within different measurement ranges.

The soft magnetic alloy of the present embodiment locally has 40 ten thousand maximum points/μm where the Fe content is higher than the surrounding Fe content³And when the ratio of the maximum points having a coordination number of 1 or more and 5 or less to the total maximum points of the Fe content is 80% or more and 100% or less, an Fe-constituting network phase is present.

Further, in the soft magnetic alloy of the present embodiment, a lattice (a lattice in which the Fe amount is smaller than the average of the total soft magnetic alloy) in which the Fe amount is lower than the threshold value is selected, and the C content of the lattice is measured to produce an integrated frequency function as shown in fig. 9. The average value of the C content in the lattice having an integrated frequency of 90% or more (hereinafter, sometimes referred to as a low Fe-high C lattice) is 5.0 times or more higher than the average C content of the soft magnetic alloy as a whole. The average C content is preferably 6.0 times or more, more preferably 7.0 times or more higher than the total amount of the soft magnetic alloy. Further, the average value of the amount of C in the low-Fe high-C lattices does not particularly have an upper limit, but is usually less than 30 times the average amount of C of the soft magnetic alloy as a whole. The integrated frequency function shown in fig. 9 is an integrated frequency function of example 5 and example 6a described later. In fig. 9, a portion where the integration frequency is lower than 80% is omitted.

The soft magnetic alloy of the present embodiment has an Fe compositional network phase and further has the above-described C amount distribution, that is, C is precipitated in a place where the Fe content is small, whereby the coercive force can be reduced and the manufacturing stability can be improved. Here, the production stability refers to a property of stably producing a soft magnetic alloy having a low coercive force even if the production conditions vary. In the soft magnetic alloy of the present embodiment, stability against a variation in heat treatment temperature described later is high, and particularly, even in heat treatment at a high temperature, a low coercive force can be maintained.

Further, the average C content of the soft magnetic alloy according to the present embodiment is preferably 3 atomic% or less. When the C content is 3 atomic% or less, the coercive force can be further reduced. The average C content of the soft magnetic alloy as a whole is preferably 0.1 at% or more and 3 at% or less, and more preferably 0.5 at% or more and 1.0 at% or less.

Further, the average B amount in the low Fe high C lattices of the soft magnetic alloy according to the present embodiment is preferably 1.20 times or more the average B amount of the entire soft magnetic alloy.

Further, the average M content of the low Fe high C lattices in the soft magnetic alloy according to the present embodiment is preferably 1.20 times or more the average M content of the entire soft magnetic alloy.

By showing the above distribution of the amount of B and/or the distribution of the amount of M in the soft magnetic alloy, that is, by precipitating B and/or M in a place where the Fe content is small, generation of a hetero phase, particularly generation of a boride in which Fe atoms and B atoms are bonded, is easily suppressed, the coercive force is easily lowered, and a soft magnetic alloy having high production stability is easily produced. The reason why the generation of boride is suppressed is considered to be that a C atom and an M atom (particularly, Nb atom) are easily bonded, and an M atom (particularly, Nb atom) and a B atom are easily bonded. That is, it is considered that the segregation of C atoms occurs in a place where the Fe atom content is small, and further, when B atoms and M atoms are segregated, the portion having C-M-B bonds is increased, and the amount of B atoms bonded to Fe atoms and becoming borides is decreased.

The method for producing the soft magnetic alloy of the present embodiment will be described below.

The method for producing the soft magnetic alloy according to the present embodiment is not particularly limited. For example, there is a method of manufacturing a thin strip of the soft magnetic alloy according to the present embodiment by a single-roll method.

In the single-roll method, first, pure metals of the respective metal elements contained in the finally obtained soft magnetic alloy are prepared and weighed so as to have the same composition as that of the finally obtained soft magnetic alloy. Then, the pure metals of the respective metal elements are melted and mixed to produce a master alloy. The method of melting the pure metal is not particularly limited, but for example, a method of melting the pure metal in a chamber by high-frequency heating after evacuation is used. In addition, the master alloy and the finally obtained soft magnetic alloy generally have the same composition.

Next, the produced master alloy is heated and melted to obtain molten metal (molten metal). The temperature of the molten metal is not particularly limited, but may be set to 1200 to 1500 ℃, for example.

Fig. 8 shows a schematic diagram of an apparatus used in the single-roll method. In the single-roll method of the present embodiment, the molten metal 32 is supplied by spraying from the nozzle 31 to the roll 33 rotating in the direction of the arrow inside the chamber 35, whereby the thin strip 34 can be produced in the direction of rotation of the roll 33. In the present embodiment, the material of the roller 33 is not particularly limited. For example, a roller made of Cu may be used.

The rotation direction of the roller 33 in fig. 8 is opposite to the rotation direction of a normal roller. By rotating the roll in the direction opposite to the normal rotation direction of the roll, the time for which the roll 33 and the ribbon 34 are in contact can be prolonged, and the ribbon 34 can be cooled more rapidly.

Further, as an advantage of rotating the roller 33 in the direction shown in fig. 8, there is an advantage that the cooling strength by the roller 33 can be controlled by controlling the gas pressure of the stripping gas ejected from the stripping gas ejecting apparatus 36 shown in fig. 8. For example, by increasing the pressure of the stripping gas, the time for which the roll 33 and the thin strip 34 are in contact can be shortened, and cooling can be reduced. Conversely, by reducing the pressure of the stripping gas, the time for which the roll 33 and the thin strip 34 are in contact can be prolonged, and cooling can be enhanced.

In the single roll method, the thickness of the obtainable thin strip can be adjusted by mainly adjusting the rotation speed of the roll 33, but the thickness of the obtainable thin strip can also be adjusted by adjusting, for example, the interval between the nozzle 31 and the roll 33, the temperature of the molten metal, or the like. The thickness of the ribbon is not particularly limited, but may be, for example, 15 to 30 μm.

Before the heat treatment described later, the ribbon is preferably amorphous. The Fe compositional network phase described above can be obtained by subjecting the amorphous ribbon to a heat treatment described later.

Further, the method for confirming whether or not the ribbon of the soft magnetic alloy before the heat treatment is amorphous is not particularly limited. Here, the thin strip is amorphous means that no crystal is contained in the thin strip. For example, the presence or absence of crystals having a particle diameter of about 0.01 to 10 μm can be confirmed by ordinary X-ray diffraction measurement. In the present embodiment, when the presence of crystals can be confirmed by ordinary X-ray diffraction measurement, the Fe compositional network phase is not obtained after the heat treatment.

The temperature of the roller 33 or the vapor pressure inside the chamber 35 is not particularly limited. For example, the temperature of the roller 33 may be 50 to 70 ℃, and the vapor pressure inside the chamber 35 may be 11hPa or less by using Ar gas whose dew point is adjusted.

In the single roll method, it is presently considered that it is preferable to increase the cooling rate to rapidly cool the molten metal 32, and it is considered that it is preferable to increase the cooling rate by increasing the temperature difference between the molten metal 32 and the roll 33. Therefore, it is considered that the temperature of the roller 33 is preferably set to about 5 to 30 ℃. However, the present inventors have found that by raising the temperature of the roll 33 to 50 to 70 ℃ by the conventional single-roll method and further setting the vapor pressure inside the chamber 35 to 4hPa or less, the molten metal 32 can be uniformly cooled, and the ribbon of the soft magnetic alloy that can be obtained before the heat treatment can be easily made into a uniform amorphous shape. Further, the lower limit of the vapor pressure inside the chamber is not particularly limited. The argon gas whose dew point is adjusted may be filled to suppress the steam to 1hPa or less, or the argon gas may be in a state of being substantially vacuum to suppress the steam to 1hPa or less.

The above-described Fe compositional network phase can be obtained by heat-treating the obtained thin strip 34. Further, the above-mentioned distributions of the C amount, B amount and M amount can be easily obtained. In this case, when the ribbon 34 is amorphous, the above-described Fe compositional network phase is easily obtained.

The heat treatment conditions are not particularly limited. The preferred heat treatment conditions vary depending on the composition of the soft magnetic alloy. The preferable heat treatment temperature is approximately 450 to 600 ℃. Among these, in consideration of manufacturing stability, it is preferable to suppress the generation of boride and maintain a low coercive force even when the heat treatment temperature is increased. In some cases, the boride formation temperature may vary depending on the composition, and a preferable heat treatment temperature may remain outside the above range.

The heat treatment time is also not particularly limited. The heat treatment time is preferably 10 minutes to 180 minutes, and more preferably 60 minutes to 180 minutes. However, there may be a preferable heat treatment time in a range out of the above range depending on the composition. By controlling the heat treatment time within the above range, B atoms and M atoms are easily segregated in a place having a small Fe content, and the coercivity can be reduced and the manufacturing stability can be improved.

As a method for obtaining the soft magnetic alloy of the present embodiment, there is a method for obtaining the soft magnetic alloy powder of the present embodiment by, for example, a water atomization method or a gas atomization method, in addition to the above-described single roll method. Next, the gas atomization method will be explained.

In the gas atomization method, a molten alloy at 1200 to 1500 ℃ can be obtained as in the single-roll method described above. Thereafter, the molten alloy is sprayed into the chamber to produce powder.

In this case, the preferable Fe network phase is finally easily obtained by setting the gas injection temperature to 50 to 100 ℃ and the vapor pressure in the chamber to 4hPa or less.

After the powder is prepared by a gas atomization method, heat treatment is performed at 550-650 ℃ for 10-180 minutes, so that the powder is prevented from being coarsened due to sintering of the powder, the diffusion of elements is promoted to reach a thermodynamic equilibrium state in a short time, deformation or stress is removed, and a Fe composition network phase is easily obtained. In addition, a soft magnetic alloy powder having excellent soft magnetic characteristics particularly in a high frequency region can be obtained.

One embodiment of the present invention has been described above, but the present invention is not limited to the above embodiment.

The shape of the soft magnetic alloy according to the present embodiment is not particularly limited. As described above, the ribbon shape and the powder shape are exemplified, but in addition to these, a bulk shape and the like are also considered.

The use of the soft magnetic alloy according to the present embodiment is not particularly limited, and the soft magnetic alloy is preferably used for a magnetic component. Examples of the magnetic member include a magnetic core. The soft magnetic alloy of the present invention can be preferably used as a magnetic core for inductors, particularly power inductors. The soft magnetic alloy of the present embodiment can be suitably used for magnetic components such as thin film inductors, magnetic heads, and transformers, in addition to the magnetic core.

Next, a method for obtaining a core and an inductor from the soft magnetic alloy of the present embodiment will be described, but the method for obtaining a core and an inductor from the soft magnetic alloy of the present embodiment is not limited to the following method.

Examples of a method for obtaining a magnetic core from a soft magnetic alloy in a thin strip shape include a method of winding a soft magnetic alloy in a thin strip shape and a method of laminating the soft magnetic alloy. When the soft magnetic alloys having a thin strip shape are laminated, a magnetic core having further improved characteristics can be obtained when the soft magnetic alloys are laminated via an insulator.

As a method for obtaining a magnetic core from a powder-shaped soft magnetic alloy, for example, a method of appropriately mixing a binder with the magnetic core and then molding the mixture using a mold is given. Further, by subjecting the powder surface to oxidation treatment, insulation coating, or the like before mixing with the binder, the specific resistance is improved, and a magnetic core suitable for a higher frequency band is obtained.

The molding method is not particularly limited, and molding using a mold, press molding, and the like can be exemplified. The type of the binder is not particularly limited, and silicone resin may be exemplified. The mixing ratio of the soft magnetic alloy powder and the binder is not particularly limited. For example, the binder may be mixed in an amount of 1 to 10 mass% based on 100 mass% of the soft magnetic alloy powder.

For example, by mixing 1 to 5 mass% of a binder with 100 mass% of soft magnetic alloy powder and compression molding the mixture using a die, a 1.6 × 10 powder filling ratio (powder filling ratio) with a volume fraction of 70% or more can be obtained⁴A magnetic core having a magnetic flux density of 0.4T or more and a specific resistance of 1. omega. cm or more in an A/m magnetic field. The above characteristics are more excellent than those of a general ferrite core.

For example, by mixing 1 to 3 mass% of a binder with 100 mass% of the soft magnetic alloy powder and compression molding the mixture with a mold under a temperature condition of a softening point of the binder or higher, the occupied area ratio can be 80% or more and 1.6 × 10 is applied⁴A powder magnetic core having a magnetic flux density of 0.9T or more and a specific resistance of 0.1. omega. cm or more in an A/m magnetic field. The above characteristics are more excellent than those of a normal powder magnetic core.

Further, by performing heat treatment as distortion correction heat treatment on the molded body constituting the magnetic core after molding, the magnetic core loss is further reduced, and the usefulness is improved.

Further, by winding the magnetic core, an inductance component can be obtained. The method of implementing the winding and the method of manufacturing the inductance component are not particularly limited. For example, a method of winding at least 1 turn or more around the magnetic core manufactured by the above method is exemplified.

Further, when soft magnetic alloy particles are used, there is a method of manufacturing an inductance component by integrating them by press molding in a state where a coil winding is built in a magnetic body. In this case, an inductance component that is high in frequency and can handle a large current can be easily obtained.

Further, when soft magnetic alloy particles are used, a soft magnetic alloy paste obtained by adding a binder and a solvent to the soft magnetic alloy particles and pasting the soft magnetic alloy particles and a conductor paste obtained by adding a binder and a solvent to a conductor metal for a coil and pasting the soft magnetic alloy paste and the conductor paste are alternately printed and laminated, and then heated and fired, whereby an inductance component can be obtained. Alternatively, an inductance component having a coil built in a magnetic body can be obtained by preparing a soft magnetic alloy sheet using a soft magnetic alloy paste, printing a conductor paste on the surface of the soft magnetic alloy sheet, and then laminating and firing the conductor paste.

Here, in the case of manufacturing an inductance component using soft magnetic alloy particles, it is preferable to use soft magnetic alloy powder having a maximum particle diameter of 45 μm or less in terms of a mesh diameter and a central particle diameter (D50) of 30 μm or less from the viewpoint of obtaining excellent Q characteristics. In order to set the maximum particle diameter to 45 μm or less in terms of the mesh diameter, a sieve having 45 μm mesh may be used, and only the soft magnetic alloy powder passing through the sieve may be used.

The Q value in the high frequency region tends to decrease as the soft magnetic alloy powder having a large maximum particle size is used, and particularly, in the case of using a soft magnetic alloy powder having a maximum particle size exceeding 45 μm in terms of the mesh size, the Q value in the high frequency region may decrease greatly. In particular, when the Q value in the high-frequency region is not regarded as important, soft magnetic alloy powder having large variations can be used. Since the soft magnetic alloy powder with large variations can be produced at a relatively low cost, the cost can be reduced when the soft magnetic alloy powder with large variations is used.

Examples

The present invention will be specifically described below based on examples.

(experiment 1)

Pure metal materials were weighed out so as to obtain mother alloys of the compositions of the respective samples shown in table 1. Then, the chamber was evacuated, and then melted by high-frequency heating to prepare a master alloy.

Thereafter, 50g of the prepared master alloy was heated and melted to obtain a metal in a molten state of 1300 ℃, and the metal was then ejected onto a roll by a single-roll method shown in fig. 8 at a predetermined roll temperature and a predetermined steam pressure to produce a thin strip. The material of the roller is Cu. The single-roll method is a method in which a thin strip is obtained by setting a rotation speed of a roll to 25m/s, a differential pressure to 105kPa, a nozzle diameter to 5mm narrow slit, a flow-down amount to 50g, and a roll diameter to 300mm under Ar atmosphere, and the thickness of the obtained thin strip is 20 to 30 μm, the width is 4 to 5mm, and the length is several tens of m. Next, each of the produced ribbons was subjected to heat treatment, and a single-plate sample was obtained.

The differential pressure is a difference between the pressure in the vicinity of the roller 33 (inside the chamber 35) and the pressure inside the nozzle 31. By the presence of this pressure difference, the molten metal is ejected from the nozzle 31 onto the roller 33.

In experiment 1, the peel spray pressure (quenching capacity), the C content, and the heat treatment temperature during the heat treatment were changed after the roll temperature was 50 ℃, the vapor pressure was 4hPa, and the heat treatment time was 60 minutes, so that each of the samples shown in tables 1 to 4 was produced. Further, the vapor pressure was adjusted by using Ar gas whose dew point was adjusted.

Further, the presence or absence of crystals was confirmed by X-ray diffraction measurement of each ribbon before heat treatment. Further, the limited-field diffraction image and the bright-field image at 30 ten thousand times were observed using a transmission electron microscope to confirm the presence or absence of microcrystals. As a result, it was confirmed that no crystal and no microcrystal were present on the thin strip of each example, and both were amorphous.

Then, with respect to each sample obtained by heat-treating each thin strip, each sample was confirmed using 3DAP (three-dimensional atom probe), and it was confirmed that each sample was composed of an Fe network phase. Further, the average C amount of the low Fe high C lattices with respect to the average C amount of the soft magnetic alloy as a whole was measured. Further, the coercive force Hc was measured. The results are shown in tables 1 to 4. It is also said that the coercivity Hc is preferably 15A/m or less when the film is heat-treated at 550 ℃ and 600 ℃ and 25A/m or less when the film is heat-treated at 650 ℃. Further, the coercive force Hc is usually 15A/m or less in the range of 550 to 650 ℃, and is further preferably 10A/m or less in the range of 550 to 650 ℃.

[ TABLE 1 ]

In the example in which the average C amount in the low-Fe high-C lattices when heat treatment was performed at 600 ℃ was 5.0 times or more the average C amount of the soft magnetic alloy as a whole, the coercive force Hc was a good value regardless of the heat treatment temperature. In contrast, in comparative examples in which the average C content of the low-Fe high-C lattices is 5.0 times or less the average C content of the whole soft magnetic alloy, the coercive force Hc is not a good value. In examples 1 to 7 in which the average C content of the total soft magnetic alloy was 3.0 at% or less, the coercive force Hc was better than that in example 8 in which the average C content of the total soft magnetic alloy exceeded 3.0 at%.

Further, the ratio of the average C content of the low-Fe high-C lattices to the average C content of the soft magnetic alloy as a whole does not change greatly from the case of heat treatment at 600 ℃ even when heat treatment is performed at 550 ℃ or 650 ℃.

(experiment 2)

The composition of the master alloy was the same as that of example 5, and the heat treatment time was changed only in the range of 1 minute to 180 minutes, and examples were produced. The results are shown in table 2.

[ TABLE 2 ]

As is clear from table 2, in each of the examples in which the average C amount in the low Fe high C lattices is 5.0 times or more the average C amount of the soft magnetic alloy as a whole, the coercive force Hc is good. In the example in which the average B content of the low-Fe high-C lattices is 1.20 times or more the average B content of the whole soft magnetic alloy, the coercive force Hc is further favorable. In addition, in the example in which the average M amount in the low-Fe high-C lattices was 1.20 times or more the average M amount of the whole soft magnetic alloy, the coercive force Hc was further excellent.

(experiment 3)

Tests were carried out under the same conditions as in experiment 1 except that the composition of the soft magnetic alloy was changed. Experiments were conducted by varying the heat treatment temperature between 550 c and 650 c at 50 c each time. Table 3 shows the change in coercivity with the change in heat treatment temperature. The magnifications of the elements in the low-Fe high-C lattice at 600 ℃ are shown in table 3. Table 4 shows the coercive force at 50 ℃ and the magnification of each element in the low-Fe high-C lattice at an appropriate temperature, which is set as an appropriate temperature for experiments performed at 50 ℃ until 450 ℃ to 650 ℃ with each change in the coercive force.

As is clear from tables 3 and 4, the average C content in the low-Fe high-C lattices for the soft magnetic alloys having the compositions changed within the appropriate range and heat-treated at an appropriate temperature was 5.0 times or more the average C content of the whole soft magnetic alloy. The coercive force of the examples in which the average C content in the low-Fe high-C lattices is 5.0 times or more the average C content of the whole soft magnetic alloy is all good.

(experiment 4)

The test was carried out under the same conditions except that the type of M was changed in example 22. The test was carried out under the same conditions except that the type of M was changed in example 69. The results are shown in tables 5 and 6.

[ TABLE 5 ]

[ TABLE 6 ]

As is clear from tables 5 and 6, the average C content in the low Fe high C lattices of the soft magnetic alloys whose compositions were changed within appropriate ranges and heat-treated at appropriate temperatures was 5.0 times or more the average C content of the entire soft magnetic alloy. The coercive force of all the examples in which the average C content in the low-Fe high-C lattices was 5.0 times or more the average C content of the whole soft magnetic alloy was good.

(experiment 5)

So as to be able to obtain Fe: 73.5 atomic%, Si: 13.5 atomic%, B: 8.0 atomic%, Nb: 3.0 atomic%, Cu: 1.0 atomic%, C: the pure metal materials were each weighed in the form of a master alloy of 1.0 atomic% composition. Then, after the chamber was evacuated, the master alloy was melted by high-frequency heating to produce a master alloy.

Thereafter, the produced master alloy was heated and melted to obtain a metal in a molten state at 1300 ℃. In experiment 5, a sample was prepared at a gas injection temperature of 100 ℃ and a vapor pressure in the chamber of 4 hPa. Vapor pressure adjustment was performed by using Ar gas subjected to dew point adjustment.

The presence or absence of crystals was confirmed by X-ray diffraction measurement of each powder before heat treatment. As a result, it was confirmed that no crystal was present in each powder, and all of them were completely amorphous.

Then, each of the obtained powders was heat-treated, and thereafter, the coercive force Hc was measured. Then, the ratio of the average C amount of the Fe compositional network phase and the low-Fe high-C lattices to the average C amount of the soft magnetic alloy as a whole was measured. The heat treatment temperature was 550 ℃ as an appropriate temperature for the samples of Fe-Si-M1-B-Cu-C composition (comparative examples 80 and 81), and 600 ℃ as an appropriate temperature for the samples of Fe-M2-B-C composition (comparative examples 82 and 83). The time of the heat treatment was set to 1 hour. In experiment 5, it was confirmed that the coercive force Hc was 50A/M or less when the temperature was increased or decreased by 50 ℃ from an appropriate temperature in the Fe-Si-M1-B-Cu-C system composition. In the Fe-M2-B-C based composition, the coercive force Hc at plus or minus 50 ℃ from an appropriate temperature is preferably 100A/M or less.

[ TABLE 7 ]

When the comparative examples and examples shown in table 7 were compared, the amorphous soft magnetic alloy powder was heat-treated to obtain an Fe compositional network structure as in the case of the ribbon, and when the coercive force Hc at the minimum was set to an appropriate temperature and the coercive force Hc at 50 ℃ and the average C content of the low Fe high C lattices at the appropriate temperature was 5.0 times or more the average C content of the soft magnetic alloy as a whole, the coercive force Hc tended to decrease as in the ribbons of experiments 1 to 4.

Claims

1. A soft magnetic alloy, wherein,

the soft magnetic alloy contains Fe as a main component and C,

in the composition of the soft magnetic alloy Fe_aCu_bM1_cSi_dB_eC_fIn the formula, a + b + c + d + e + f is 100, b is more than or equal to 0.1 and less than or equal to 3.0, c is more than or equal to 1.0 and less than or equal to 10.0, d is more than or equal to 0.0 and less than or equal to 17.5, e is more than or equal to 6.0 and less than or equal to 13.0, and 0.0<f is less than or equal to 4.0, M1 is more than one selected from Nb, Ti, Zr, Hf, V, Ta, Mo, P and Cr,

the average value of the C content in the lattice having an Fe content lower than the average value is 5.0 times or more the average C content of the whole soft magnetic alloy, counted from the lattice having a low C content, and the cumulative frequency is 90% or more.

2. The soft magnetic alloy according to claim 1,

the average M1 amount in the lattice having an integrated frequency of 90% or more is 1.2 times or more the average M1 amount of the whole soft magnetic alloy, counted from the point of the lattice having a lower Fe amount than the average C amount.

3. A soft magnetic alloy, wherein,

the soft magnetic alloy contains Fe as a main component and C,

the average value of the C content in the lattice having an Fe content lower than the average value, counted from the start of the lattice having a low C content, at a cumulative frequency of 90% or more is 5.0 times or more the average C content of the entire soft magnetic alloy.

4. The soft magnetic alloy according to claim 3,

the average M2 amount in the lattice having an integrated frequency of 90% or more is 1.2 times or more the average M2 amount of the whole soft magnetic alloy, counted from the point of the lattice having a lower Fe amount than the average C amount.

5. The soft magnetic alloy according to claim 1 or 3,

the average C content of the soft magnetic alloy as a whole is 3 atomic% or less.

6. The soft magnetic alloy according to claim 1 or 3,

the average B amount in the lattice having an Fe amount lower than the average is 1.2 times or more the average B amount of the whole soft magnetic alloy in the lattice having a cumulative frequency of 90% or more, counted from the start of the lattice having a low C content.

7. A magnetic component comprising the soft magnetic alloy according to any one of claims 1 to 6.